The spectral variability of HD 192639 and its implications for the star's wind structure

Citation
G. Rauw et al., The spectral variability of HD 192639 and its implications for the star's wind structure, ASTRON ASTR, 366(2), 2001, pp. 585-597
Citations number
25
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
00046361 → ACNP
Volume
366
Issue
2
Year of publication
2001
Pages
585 - 597
Database
ISI
SICI code
0004-6361(200102)366:2<585:TSVOH1>2.0.ZU;2-R
Abstract
We report the analysis of an extensive set of spectroscopic data of the O(f ) supergiant HD 192639. A Fourier analysis of our time-series reveals a rec urrent variability with a "period" of roughly 4.8 days which is most promin ent in the absorption components of the He II X 4686 and H alpha P-Cygni pr ofiles. The same periodicity is also detected in the blue wing of several a bsorption lines (e.g. H beta). The variations of the absorption components correspond most probably to a cyclical modulation of the amount of stellar wind material along the line of sight towards the star. The 4.8-day period affects also the morphology of the double-peaked He II lambda 4686 and HQ. emission components, although these emission components display also variat ions on other (mainly longer) time scales. The most likely explanation for the 4.8-day modulation is that this cycle reflects: the stellar rotational period (or half this period). We find that the most important observational properties can be explained - at least qualitatively - by a corotating int eraction region or a tilted confined corotating wind.